When I first went paleo I had a bout like yours, first week or so was carb withdrawals. Once it passed it was great.

I think it's different for everybody, you may actually "need" some carbs. I myself do a bit better since having put a few potatoes back in.

You are simply not fueling your body with enough animal fat and animal protein to replace all those carbs you used to eat. A very common problem with new to paleo people.

All the carbs you used to eat turned directly into sugars that you used for energy. Paleo style, you need more meat and fat. At age 30 and you are almost at your weight goal, I suspect you need somewhere around 2500 to 2800 cal a day or a little less. Tract your caloric intact as well as the percentages of protein and fat on http://www.fitday.com Many of us eat 75-80% fat, 10-15% protein and 5% or less in carbs.

Try using more coconut oil. Panfry eggs in the c oil...or just take with you a jar of coconut oil and have a couple of spoonfulls mid morning. Each tablespoon has 117 calories & 14 grams of sat fat. Make sure the jar is leakproof because it turns to liquid at 76 degrees.

The other part of paleo is Vit D3...either getting 20 min a day of full sun half naked...10 min on a side or supplementing with 5-10000IU daily with Vit D3. Vit D3 assists T cells to be activated to fight off invading bacteria and virus.
If you supplement, take in the morning as it has a tendency to cause insomnia in some people if taken at night.

http://paleohacks.com/questions/28750/do-you-know-how-vit-d-assists-the-body-in-warding-off-diseases#axzz1IUQ5SoKn

You may have inflamation that prior to paleo you were feeding with the carbs & sugar and now your body is complaining. You are doing a lot of healing with paleo. And Vit D3 has a subtle positive effect on mood...whether from sun or supplementing.

Hang in there. You will absolutely enjoy the way you feel once you teach your body it doesn't need a lot of carbs.

I had no energy for the first six weeks - I couldn't exercise at all, was dizzy, tired, etc. Right at the six week mark I noticed a big change, and since then have had way, way more energy almost everyday. My wife started eating Paleo a little while ago and only had the "carb flu" for about 3-4 days.

Point is it's normal, and the length and severity are different for everyone.

I'm no expert but I'd suggest eating more fat; that's your main source of energy now. I would also suggest not eating sugar of any kind until this passes. Eating more fruit or potatoes will just make it last longer. I'm sure there's a scientific explanation but I think it's because your body needs to "switch" to using fat rather than sending you signals that it's hungry (the fatigue) which used to be rewarded with quick energy food like easily digestible carbs.

I agree with Scott about the carb withdrawals. I would like to add that carb withdrawal can also cause you to need additional potassium. My husband and I both had problems with this. Have you noticed you're urinating a lot more than usual since you started paleo? Are you finding yourself much thirstier than usual? When you say "tired", do you mean you feel weak? Are you feeling occasionally dizzy or lightheaded?

If so, I suggest buying some potassium tabs and taking 4 tabs at once. If you feel TONS better in about 30 minutes, there's your answer. Once your body has adjusted, you shouldn't need them anymore.

I hope this helps!

It could be carb withdrawal, and it could be side effects of your body detoxing. It's also possible that there are some vitamins or minerals that you aren't getting now. Not everyone's body is the same.

Are you getting any green vegetables? Green veggies and to a small degree carrots (I really notice a difference with my night blindness if I don't eat carrots and I'm not adding another supplement) are essential to me, and paleo means different things to different people. For me, it's combination of meats, fish, veggies and occasional fruit. To others, paleo means all meat and fat. To others, it's something in between. Some consume dairy, others don't, so when anyone says "I've been paleo now for __ amount of time" it is really a vague term. You'll need to figure out what is right for you based on how you feel, but I'd say you're still in the window for carb w/d (which I've never experienced, but I know others do and it's very real) or detox.

Just to re-iterate what others have said...

Your body is adjusting to a new source of fuel. There's a reason we say to give it 30 days. It often takes that long to adjust fully. I also do much better when I eat more fat. And yes, you may just need more calories. Eat when you're hungry, and eat to satiety.

Sleep more. 8-9 hours a night in a pitch black room. Limit artificial/electronic light sources before bed (computer, television), and take magnesium or melatonin if necessary.

Tinker with your ratios some. You may also need more carbs. I bet it's really just that you need more fat, but everyone is different. Do what works for you.

Have you tried taking a brisk walk instead of a nap when you feel tired in the afternoon?

Personally, as a chronic dieter, I had a lot of trouble eating enough fat, and eating enough food in general. I was totally convinced that I had to deprive myself to lose weight. Turns out that's not true.

How much sleep are you getting?

Having a downside for 2-3 weeks is pretty normally depending on how your diet was before you switch to paleo. Some people have a very hard time dealing with lower carbs (non processed) others have no issues at all.

Give it some time, make sure you are getting sleep as well how is your caffeine intake?

i am in withdrawls now. its killing me. i am usually so needy of a huge amount of adrenaline via exercise each day- its my main stress release- and now on this diet, although i am enjoying it for the most part, i am a bit stressed over being so lethargic. its like an alien has come over and taken over my body. i'd be very surprised if i am not eating enough fat or protein or calories cuz i am like always full. i really am not hungry a whole lot and when i do eat, its mostly good fats and good proteins so man, i fuel up super fast and stay FULL for quite a long time. i was so dozy a few mins ago that i went and ate an apple. its like i NEEDED some instant sugar. YUCK. now, i wish i had more nuts or something cuz i guess thats what i need. i am on my 2-3rd week of paleo and i mean good prots, fats, dairy (whole fat) and some fruits and veggies but man i have so limited my fruit and veg intake DRASTically. i used to really love those items but now, i am trying to do 80 grams of carbs/day. i also (try) to do quality training as well. (running intervals on some days while I do 30 minutes lactate threshold sets at the gym (ie: crossfit)- and its ROUGH.

I worked with a naturapathic doctor who had me eating very similiar to paleo. I too was very,very tired. She told me because i was dropping bodyfat pretty quickly, I was also depleting my potassium and magnesium levels. she gave me a supplement of pot/mag to take for awhile and that did the trick. I had a lot of energy and felt great! Anyway, just something you can research for yourself. It may do the trick for you too.